1. Field of the Invention
This invention relates generally to devices for use in administration of intravenous solutions, and especially for filters for use in such systems.
2. Description of the Prior Art
When administering intravenous solutions, it is generally desirable to filter such solutions just prior to their infusion into a patient in order to remove solid particulate matter such as bacteria, undesirable solids, and any particulates greater than a few microns. Known type filters for effecting this filtering are generally employed, such as hydrophilic filters. Such filters, after being wetted, are capable of passing liquid through the pores thereof while simultaneously blocking air or like gases. Thus, such filters can substantially remove any of the particulates which are considered to be undesirable.
Also, it is extremely important that any air or other gases which might be present in the solution be blocked and preferably eliminated from the system prior to the administration of the solution into a patient.
However, known type devices for effecting the above functions oftentimes leave much to be desired. A common problem with such devices is that they may filter out the particulate materials, but gas blockage of the filter can result with subsequent blocking of the entire filter and prevention of the fusion flow therethrough.
Another common problem with known type devices is that even though gases such as air may be blocked by the filter, they fail to completely expel or eliminate such air. This, of course, is very important so that there is no possibility of the gases either becoming re-entrained with the solution and/or being infused into the patient with oftentimes fatal results.
Several known patents which are pertinent to the present invention are U.S. Pat. Nos. 4,004,587 and 4,031,891.
In U.S. Pat. No. 4,004,587, a filter device which is conical in nature is used with tubing for administration of parenteral fluids. The filter device is conical and provided with two window sections in the filter support housing, one of the window sections being covered with a hydrophilic filter, and the other window section with a hydrophobic filter, However, the first and second separate filter members are in parallel flow position so that simultaneous flow can occur therethrough in parallel relationship. This is quite different from the device of the present invention.
U.S. Pat. No. 4,031,891 shows a filter arrangement having a housing with both a hydrophobic and a hydrophilic filter element. However, the position of the elements in this device is substantially different and unlike that of the structure of the present invention. In this patent both the fluid and air are purged from inside the tube. In the present device, the one filter separates air from the fluid prior to the fluid itself passing through the hydrophilic membrane and subsequent infusion into a patient.
Furthermore, in U.S. Pat. No. 4,004,587, air is expelled from inside the cone, through the hydrophobic membrane and into the fluid path. This arrangement is fine for initial priming, but can be dangerous is air should enter the system when connected to a patient.
None of the known prior art devices offer the new and novel features of the present invention.